Internal combustion engines are known to operate with single or multiple injections of fuel into a combustion chamber of the engine. Multiple injections of fuel may be accomplished by either multiple fuel injectors or by a single fuel injector that is constructed and operated to allow for multiple injections. Typically, multiple injections of fuel include a pilot and a main injection. The relative volume of the pilot and main injections may differ considerably. Generally, the pilot injection is small in volume compared to a volume of the main injection.
The timing of fuel injection for desired engine performance depends on whether the engine is operating with or without pilot injections. Switching pilot injection on or off can affect engine performance. For example, engine roughness often occurs when engine operation is changed by adding or removing pilot fuel injection to a main fuel injection.
Accordingly, there is to eliminate engine performance problems related to the activation or deactivation of pilot injection in the fuel injection process.